Mixed solvent solution of polymer for paper treatment



United States Patent US. Cl. 117-155 5 Claims ABSTRACT OF THE DISCLOSUREThe method for waterproofing and adhesion strengthening comprising:coating a paper or cardboard with a composition*;comprising a syntheticresin dissolved in a solvent, said solvent consisting of xylene and oneof the following, fnethylene chloride, methyl ethyl ketone andperchloroethylene, the proportion of xylene to the other being 5 to 1-2.

This invention relates to a novel plastic solution formoisture'resistance water proofing and adhesion strengthening and moreparticularly it pertains to a thermoplastic resin solution.

Hitherto, it has been Well known that starting materials for'plastics,particularly thermoplastic resins such as vinyl chloride, celluloseacetate, polystyrenes, methacrylates, polyethylene, Teflon (trademarkfor polytetrafluoroetliylene resin), polyamide and the like, for examplestyrene monomer are usually subjected to an emulsion polymerization toform a synthetic latex, or those resins are dissolved in a suitablesolvent to form a solvent type coating material which would be used formiscellaneous purposes, for example, water proofing and adhesionstrengthening in the working of papers, adhesion of shaped materials,lacquer finishing and the like.

When applied to the working of paper, adhesion, coating and the like,however, the known latex and solvent type coating materials, forexample, such as polystyrene latex and coating material are likely todevelop small fissures with the lapse of time and therefore becomeineffective, as usually observed and experienced.

To obviate the above disadvantages, the inventor has carried out manystudies from the various aspects and found that the suitability of thesolvent to the plastics plays the most important part.

As solvents for the plastics, especially for the thermoplastic resinsthere may be mentioned quick drying solvents, intermediate dryingsolvents and slow drying solvents. Hitherto these solvents have beenusually used independently or in the form of mixture thereof.Aforementioned disadvantages have resulted from the unsuitability of thesolvents.

The inventor has prepared and tested various kinds of mixed solvents bytaking into consideration the proportion of the miscellaneous solvents.It has been found that the solvent consisting essentially ofintermediate drying solvent xylene and quick drying methylene chlorideor methyl ethyl ketone, or intermediate drying perchloroethylene is themost suitable for plastic.

According to the present invention, it is essential to adequately selectthe proportion of the other solvents to xylene. The recommendedproportion of xylene to other solvents is 5 to 1-2.

When the plastic solution prepared by using a solvent in the aforesaidproportion is used in the working of paper, for example, strengtheningof corrugated boards, adhesion or coating of plastics, no fissures areobserved on the strengthened, adhered or coated surfaces and thesurfaces hold their favorable effects for an extended period of time.

The plastic solution for moisture resistance water proofing and adhesionstrengthening of the present invention may be mixed with a suitableplasticizer according to its use.

Further, it will be appreciated that a plasticizer, produced by addingan emulsifier consisting essentially of a nonionic surface active agentto a parafiine either in a liquid or solid form, heating and thencooling the mixture slowly, is eminently suitable for the polystyrenesolvent solution.

The exemplified proportion of the components of the fundamental plasticsolution for moisture resistance water proofing and adhesionstrengthening contemplated by the invention will be shown in thefollowing:

Kg. Xylene 1 5 Methylene chloride 1 l Plasticizer 1 0.03 Polystyrene 1Xylene 1 8 Perchloroethylene 1 3 Polystyrene l 1 Solvent.

The above fundamental plastic solutions are preferable to the use afterdilution with additional solvent, according to the use.

The fundamental plastic solutions thus produced are considerablyeffective when used for the working of papers, the strengthening ofcorrugated board, the adhesion of plastic products as well as waterproofing and strengthening of fibrous products. The fundamental plasticsolution may also be colored by adding certain dyestuffs.

To strengthen the corrugated board, for example, by using thefundamental plastic solutions of the invention, it is preferred to usethe above mentioned fundamental plastic solution (1) which is added aplasticizer in order to increase the impact, breaking, compressive andbending strengths. For strengthening the corrugated board, 7 kg. of thefundamental plastic solution 1) for example, is mixed with 8 kg. of thesolvent and the corrugated board is immersed in this mixture for fiftyseconds and then dried for twenty four hours to provide the toughenedcorrugated board.

As the result of the various tests carried out on corrugated boardtreated with the plastic solution of the present invention, it has beenascertained that the said.

strengthened corrugated board is less expensive and has more excellentproperties than the conventional ones.

The breaking and impact strengths of two corrugated boards comprising anoutside liner (C in 230 g.), a core (metasemichemical pulp in g.) and arear side liner (C in 200 g.) one of which Was strengthened with thepresent plastic solution and the other not treated, and the compressivestrength of two boxes in the dimension of 585 x 290 x 273 mm. one ofwhich was manufactured 1 3 4 by the strengthened corrugated board andthe other by ening as claimed in claim 1, wherein said composition isthe commercial corrugated board are respectively shown 5 kg. of xylene,1 kg. of methylene chloride,'0.03 kg. of in the following table.plasticizer, and 1 kg. of polystyrene.

Strengthened Not strengthened Number of samples 1 2 8 1 2 3 Subjects:

Breaking strength (kgJcmfl):

Maxlmum Average 13.4 13.3 13.2 9.33 9.17 9. 33

Total average .Q 13. 3 9. 31

Impact strength (kg/emfl):

Maximum 73v 0 74. 0 74. 0 54. 0 58. 0 54. 0 Minimum 65.0 67.0 66.0 47.048.0 48.0

Average 69. 4 69. 4 70. 1 51. 2 54. 8 51.9

Total average 69. 6 52.6

Compressive strength:

Compressive load (kg.) 480 540 480 270 300 270 Compression amount (mm.)16 14 15 14 18 16 Average compressive load (kg) 500 247 Average ofcompression amount (mm.) 15 16 Remarks: I 5. The method forwaterproofing and adhesion strength- (1) Applied quantity: g. per m? 60ening as claimed in claim 1, in which the plastic solu- (2) Watercontent: tion is mixed with dyestuffs.

Strengthened one percent 10 Not strengthened one percent 1.5 ReferencesCited Moreover, no arsenic substance, lead and formaldehyde UNITEDSTATES PATENTS was detected by tests carried out on the solution leached2,207,623 7/ 1940 Kauppi et al. with 2 ml. of 4% acetic acid per 1 cm.of the surface 2,348,447 5/1944 B o k, area of the strengthenedcorrugated boards in accordance 2,397,093 3/1946 Dreyfus t a1, with thehygienic method agreed by Japan Pharma- 3,046,245 7/ 1962 Kern et a1.ceu'tical Association.

I claim: OTHER REFERENCES l A methPd for waterproofing and FengtheningBoundy et al.: Styrene, Its Polymers, Copolymers and PIISIHg Z coating apaper 01 cardboard with B. COI'DPPSIUOH Derivatives, Reinhold Pull CorpNew k 1952 pages comprising polystyrene dissolved in a solvent, saidsol- 426 and 427 TP 986 s7 B6 vent consisting of xylene and one of thefollowing: 40 Worth, Aibin The Chemistry and Technology of methylenechloride, methyl ethyl ketone and perchloro- W 1 ethylene, theproportion of xylene to the other being 5 fif ggg 8 2 2 3 5 98?" NewYork 1956 2. The method for waterproofing and strengthening as MORRISLIEBMAN Primary Examiner claimed in claim 1, wherein said composition is8 kg. of xylene, 3 kg. of perchloroethylene and 1 kg. of poly-DERRINGTON Asslstant Exammer styrene.

3. The method for waterproofing and adhesion strengthening as claimed inclaim 1, in which a suitable plas- 26032.8, 33.6, 33.8 ticizer isincorporated in said composition. H

4. The method for waterproofing and adhesion strength-

